Method and system for providing a setup timer in a sip-based network

ABSTRACT

A system and method for providing a setup timer in a SIP-based network including initiating a session by transmitting one or more messages to a first user. The system and method also comprises starting a first timer upon transmitting the one or more messages, wherein the first timer is configured to expire after a first predetermined time period. The system and method further comprises starting a second timer upon transmitting the one or more messages, wherein the second timer is configured to expire after a second predetermined time period. The system and method furthermore comprises transmitting one or more instructions upon expiration of at least one of the first timer and the second timer, and taking one or more actions based at least in part on the one or more instructions.

BACKGROUND INFORMATION

Session Initiation Protocol (SIP) is a call control signaling protocolfor Internet Protocol (IP) network. SIP is designed to bedevice-agnostic—that is, it is intended to provide a highly flexiblecall signaling capability that is not tailored to the capabilities ofany particular device. Analog telephone signaling, on the other hand, isdevice-specific and highly constrained because of the historical legacyof the services delivered to the device. As a result, many call featuresavailable in traditional analog telephone devices (e.g., notification ofend terminals status) are not easily integrated in a SIP-based networkbecause SIP-based network elements may communicate only to adjacentSIP-based network elements. For example, one or more SIP messages may betransmitted between end terminal A and end terminal B to establish a SIPsession (e.g., call session). Currently, an initiation process of a SIPsession between end terminal A (e.g., caller) and end terminal B (e.g.,callee) may take a long period of time (e.g., minutes). During theinitiation process, SIP service providers may not be capable ofdetermining whether a valid SIP session has been established between endterminal A and end terminal B. For example, the SIP service providersmay receive one or more messages from intermediate devices between endterminal A and end terminal B, however, SIP service providers may nottake any action for a long time until receiving one or more messagesfrom the end terminal B. Therefore, the SIP service providers may haveto wait for a long period of time before taking one or more actionsassociated with the initiation process of the SIP session.

BRIEF DESCRIPTION OF THE DRAWINGS

In order to facilitate a fuller understanding of the exemplaryembodiments of the present inventions, reference is now made to theappended drawings. These drawings should not be construed as limiting,but are intended to be exemplary only.

FIG. 1 illustrates a block diagram of a SIP-based network system forproviding SIP setup timers, in accordance with an exemplary embodiment.

FIG. 2 illustrates a block diagram of an exemplary implementation whereSIP setup timers are embedded in a FTTP network, in accordance with anexemplary embodiment.

FIG. 3 illustrates a block diagram of an exemplary implementation whereSIP setup timers are embedded in an ATA network, in accordance with anexemplary embodiment.

FIG. 4A illustrates a flow diagram for providing integrated setup timersin a SIP-based network for connecting a time-division multiplex (TDM)device to a SIP device, in accordance with an exemplary embodiment.

FIG. 4B illustrates a flow diagram for providing integrated setup timersin a SIP-based network for connecting a first SIP device to a second SIPdevice, in accordance with an exemplary embodiment.

FIG. 5A illustrates a flow diagram for providing independent setuptimers in a SIP-based network for connecting a time-division multiplex(TDM) device to a SIP device, in accordance with an exemplaryembodiment.

FIG. 5B illustrates a flow diagram for providing independent setuptimers in a SIP-based network for connecting a first SIP device to asecond SIP device, in accordance with an exemplary embodiment.

FIG. 6 illustrates a flow diagram of a method for implementing SIP setuptimers in accordance with exemplary embodiments.

These and other embodiments and advantages will become apparent from thefollowing detailed description, taken in conjunction with theaccompanying drawings, illustrating by way of example the principles ofthe various exemplary embodiments.

DETAILED DESCRIPTION OF EMBODIMENTS

A system and process of an exemplary embodiment provides one or moretimers provided between end terminals to enable SIP service providers totake one or more overflow actions associated with an initiation processof an SIP session. For example, the one or more timers may provide theSIP service providers with information (e.g., a sequential order inwhich timers expired) to determine one or more issues associated withthe end terminals and take one or more actions. In an exemplaryembodiment, a plurality of timers may be provided between the endterminals with each timer set to expire at different predetermined timeperiods. The plurality of timers may provide information and/or one ormore signals to the SIP service providers to take one or more actionsbased at least in part on a predetermined logic.

The description below describes SIP devices, SIP servers, userinterfaces, IP networks and other network elements that may include oneor more modules, some of which are explicitly shown, others are not. Asused herein, the term “module” may be understood to refer to computingsoftware, firmware, hardware, and/or various combinations thereof. It isnoted that the modules are exemplary. The modules may be combined,integrated, separated, and/or duplicated to support variousapplications. Also, a function described herein as being performed at aparticular module may be performed at one or more other modules and/orby one or more other devices instead of or in addition to the functionperformed at the particular module. Further, the modules may beimplemented across multiple devices and/or other components local orremote to one another. Additionally, the modules may be moved from onedevice and added to another device, and/or may be included in multipledevices. It is further noted that the software described herein may betangibly embodied in one or more physical media, such as, but notlimited to, a compact disc (CD), a digital versatile disc (DVD), afloppy disk, a hard drive, read only memory (ROM), random access memory(RAM), as well as other physical media capable of storing software,and/or combinations thereof. The functions described as being performedat various components may be performed at other components, and thevarious components may be combined and/or separated. Other modificationsalso may be made.

FIG. 1 illustrates a block diagram of a SIP-based network system forproviding SIP setup timers, in accordance with an exemplary embodiment.System 100 illustrates an exemplary system for supporting SIPcommunication, in particular system 100 enables a SIP service providerto take one or more actions upon expiration of one or more timersbetween end terminals. As illustrated, end terminal A 104 may include aplurality of auxiliary end terminals. For example, end terminal A104 mayinclude auxiliary end terminal A1 104 and/or auxiliary end terminal A2104. In an exemplary embodiment, the auxiliary end terminal A1 104 mayinclude a SIP device 110 and a User Interface 114, operatively coupledto each other. SIP Device 110 may include a SIP User Agent 112 forcommunicating across SIP Network 120 to a SIP Server 122. In anotherexemplary embodiment, the auxiliary end terminal A2 104 may include atime-division multiplex (TDM) device 118 coupled to a gateway 402, via aTDM network 126. The gateway 402 may operatively couple thetime-division multiplex (TDM) device 118 to the SIP Network 120. SIPServer 122 may provide communication to end terminal B 106 through SIPNetwork 124. As shown, end terminal B 106 may include one or more SIPdevices, for example, SIP Element 130 and SIP Element 132. The endterminal A 104 may establish a communication session with the endterminal B 106 through SIP Network 120. For example, the communicationsession may be a call session (e.g., a telephone call session), a datatransmission session (e.g., an Internet session), and a video session(e.g., transmission of video images). The various network elements ofsystem 100 may be further duplicated, combined and/or integrated tosupport various applications and platforms. Additional elements may alsobe implemented in the system to support various applications. ASIP-based network may also include an IP network, packet switched basednetwork or other type of network. The elements referred to in theFigures may include other network or packet switched based elements. Forexample, the elements referred to as “SIP” may include other networkdevices, elements, components, etc.

SIP Device 110 may represent a device that manages User Interface 114.User Interface 114 may include a traditional telephone (e.g., awire-line telephone) and other data communication device using voicebandor other signaling, including but not limited to data modems, facsimiledevices, teletype (TTY) equipment, etc. User Interface 114 may be adigital telephone system, wireless phone system, cordless telephonesystem, mobile phone system, satellite phone system, semi-cordless phonesystem, IP telephone system and/or any other known telephone systems.According to an exemplary embodiment, User Interface 114 may be an IPtelephone system which may include any computer device, orcommunications device including, for example, a personal computer (PC),a workstation, a mobile device, a handheld PC, a personal digitalassistant (PDA), an alert device, a receiver, and other similar devicescapable of communicating with one or more other devices. SIP Device 110may contain SIP User Agent 112. SIP User Agent 112 may be integratedwith SIP Device 110 or remote from SIP Device 110. SIP User Agent 112may perform networking between SIP signaling and user interface actions.For example, SIP User Agent 112 may manage an exchange of media (e.g.,audio, etc.) between User Interface 114 and a Real Time Protocol (RTP)media stream of a media session set up by the SIP signaling. SIP Device110 may originate calls to and receive calls from other users. SIPDevice 110 may communicate through SIP Network 120 to SIP Server 122.

The time-division multiplex (TDM) device 118 may be a digital telephonesystem, wireless phone system, cordless telephone system, mobile phonesystem, satellite phone system, semi-cordless phone system, and/or anyother known time-division multiplexing systems. Also, the gateway 402may be an interface between the time-division multiplex (TDM) device 118and the SIP Network 120. Also, the gateway 402 may be an interfacebetween a network (e.g., time-division multiplexing network) associatedwith the auxiliary end terminal A2 104 and the SIP Network 120. In anexemplary embodiment, time-Division Multiplexing (TDM) network 126 maybe a type of digital and/or analog multiplexing network. For example,TDM network 126 may be a synchronous TDM network and/or a statisticalTDM network.

SIP Server 122 may represent a SIP proxy or application server that actson behalf of SIP Device 110. For example, SIP Server 122 may manage aSIP Address of Record (AOR) on behalf of SIP Device 110. SIP Device 110may register with SIP Server 122 and send SIP signaling through SIPServer 122 to other SIP elements, such as SIP Element 130 and SIPElement 132. For example, a call to the SIP AOR may be delivered to SIPServer 122, which in turn delivers the call to SIP Device 110. SIPServer 122 may perform some service on behalf of SIP Device 110, or maysimply forward SIP messages to and from SIP Device 110. SIP Device 110communicates through SIP Network 124 to SIP Element 130 and/or SIPElement 132.

SIP Element 130 and SIP Element 132 at the end terminal B 106 mayrepresent users with which the user of SIP Device 110 communicates. SIPElement 130 and SIP Element 132 may be a SIP Device, SIP Server, and/orother SIP enabled device. SIP Element 130 and SIP Element 132 may be adigital telephone system, wireless phone system, cordless telephonesystem, mobile phone system, satellite phone system, semi-cordless phonesystem, IP telephone system and/or any other known telephone systems.According to an exemplary embodiment, SIP Element 130 and SIP Element132 may be an IP telephone system which may include any computer device,or communications device including, for example, a personal computer(PC), a workstation, a mobile device, a handheld PC, a personal digitalassistant (PDA), an alert device, a receiver, and other similar devices.In addition, SIP Element 130 and SIP Element 132 may also represent aPSTN device that may be reached by a gateway that, directly orindirectly, acts as a SIP User Agent. For example, the gateway may beoperatively couple a PSTN device and IP network and may convert one ormore messages from PSTN format to SIP format, and vice versa.

The timer module 116 may be associated with the one or more intermediatenetwork devices (e.g., SIP server 122) and/or one or more intermediatenetworks (e.g., SIP networks 120 and/or 124). Also, a plurality of timermodules 116 may be associated with the one or more intermediate networkdevices and/or one or more intermediate networks. In an exemplaryembodiment, the timer module 116 may be integrated with the one or moreintermediate network devices and/or the one or more intermediatenetworks. In another exemplary embodiment, the timer module 116 may bean external device operatively coupled to the one or more intermediatenetwork devices and/or the one or more intermediate networks. Also,timer module 116 may be associated with any intermediate network deviceor devices between the SIP device 110 and the SIP Element 130 and/or theSIP Element 132. As illustrated in FIG. 1, the timer module 116 may bean external device operatively coupled to the SIP server 122. In anotherexemplary embodiment, the timer module 116 may be integrated (e.g., partof) with the SIP server 122. In another exemplary embodiment, the timermodule 116 may be an external device operatively coupled to the SIPserver 122. Further, the timer module 116 may be associated with the SIPdevice 110, the SIP Element 130 and/or the SIP Element 132. In exemplaryembodiments, the timer module 116 may be integrated with the SIP device110, the SIP Element 130 and/or the SIP Element 132. In some otherexemplary embodiments, the timer module 116 may be an external deviceoperatively coupled to the SIP device 110, the SIP Element 130 and/orthe SIP Element 132. Moreover, the timer module 116 may be one or moreindependent intermediate network elements operatively coupled to the SIPdevice 110 and the SIP Element 130 and/or the SIP Element 132. In anexemplary embodiment, the timer module 116 may be an independent networkdevice interposed between the SIP server 122 and the SIP network 124.

Also, the timer module 116 may be managed by the SIP server 122 and/or adisparate entity (e.g., an independent service provider). In anexemplary embodiment, the timer module 116 may be managed by the SIPserver 122. One or more timers of the timer module 116 may expire aftera predetermined time period and the timer module 116 may transmit one ormore messages/signals to the SIP server 122 to notify the SIP server122. Upon reception of the one or more messages/signals from the timermodule 116, the SIP server 122 may take one or more overflow actionsbased at least in part on a predetermined logic stored in the SIP server122. In another exemplary embodiment, the timer module 116 may bemanaged by a disparate entity (e.g., an independent service provider).The disparate entity may position the timer module 116 between the endterminal A 104 and the end terminal B 106. The one or more timers of thetimer module 116 may expire after a predetermined time period and thetimer module 116 may transmit one or more messages/signals to thedisparate entity. Upon the reception of the one or more messages/signalsfrom the timer module 116, the disparate entity may take one or moreoverflow actions and/or instruct one or more network devices to take oneor more overflow actions based at least in part on predetermined logics.Further, the timer module 116 may be managed by the SIP server 112 andthe disparate entity in cooperation.

The one or more timers of the timer module 116 may be set to expireafter a predetermined time period. For example, the predetermined timeperiod associated with the timer module 116 may be determined by a userassociated with the end terminal A 104, a user associated with the endterminal B 106, and/or the disparate entity. Also, the predeterminedtime period associated with the timer module 116 may be dynamicallydetermined by the user associated with the end terminal A 104, a userassociated with the end terminal B 106, and/or the disparate entity. Forexample, the predetermined time period associated with the timer module116 may be determined based at least in part on a SIP session (e.g.,call session), user identities, one or more user preferences (e.g.,different user may set different amount of time before cancelling theSIP session initiation process), time of a SIP session (e.g., a shortertime period may be associated with later in the day), one or more userselections (e.g., end terminal A may select to establish a SIP sessionwith end terminal C, in the event that end terminal B does not respond)and/or other characteristics associated with the user.

For example, the timer module 116 may include a plurality of timersinterposed between the end terminal A 104 and the end terminal B 106.For example, the timer module 116 may include two timers interposedbetween the end terminal A 104 and the end terminal B 106. The twotimers may be located at one location or two disparate locations betweenthe end terminal A 104 and the end terminal B 106. Also, the two timersmay be set to expire at substantially the same time or set to expireafter disparate periods of time. Further, the timer module 116 mayinclude three timers interposed between the end terminal A 104 and theend terminal B 106. The three timers may be set to expire atsubstantially the same time or set to expire after disparate periods oftime. For example, the first timer of the timer module 116 may be set toexpire after 10 seconds, a second timer of the timer module 116 may beset to expire after 20 seconds, and a third timer of the timer module116 may be set to expire after 30 seconds. In addition, the three timersmay be located at one location, two disparate locations, or threedisparate locations between the end terminal A 104 and the end terminalB 106.

FIGS. 2 and 3 show exemplary implementations of a SIP Device. FIG. 2illustrates an exemplary implementation where a SIP Device is embeddedin a Fiber-to-the-Premises (FTTP) network, according to an exemplaryembodiment. FIG. 3 illustrates an exemplary implementation where a SIPDevice is embedded in an Analog Telephone Adapter (ATA) network,according to an exemplary embodiment. Other implementations with otherdevices and/or networks may also be realized.

As shown in FIG. 2, User Interface 114 may be operatively coupled to SIPDevice 110. SIP Device 110 may be embedded in Optical Network Terminal(ONT) 210 or otherwise integrated with Optical Network Terminal (ONT)210. ONT 210 may be operatively coupled to an Optical Line Terminal(OLT) 230 with a Passive Optical Network (PON) 220. According to anexemplary application, OLT 230 may be located at a Central Office. ONT210 may be operatively coupled over PON 220 to the OLT 230, which inturn operatively coupled to the SIP Server 122 through the SIP network120. According to an exemplary application, OLT 230 may maintain an IPconnection between SIP Device 110 on the ONT 210 and the SIP network120. In this exemplary application, the OLT 230 may not process SIPsignaling.

FIG. 3 illustrates SIP Device 110 embedded in an Analog TelephoneAdapter (ATA) 310 in a home or other location that subscribes to abroadband service, such as DSL or cable modem. In accordance with anexemplary embodiment, User Interface 114 may be operatively coupled toSIP Device 110. ATA 310 may be operatively coupled to Broadband Router320, which in turn may be operatively coupled to a DSL or cable modem330, which in turn may be operatively coupled to SIP network 120 throughwhich the SIP Device 110 may communicate with SIP Server 122. Thevarious network elements of systems 200 and 300 may be furtherduplicated, combined and/or integrated to support various applicationsand platforms. Additional elements may also be implemented in thesystems described above to support various applications.

FIG. 4A illustrates a flow diagram for providing integrated setup timersin a SIP-based network for connecting a time-division multiplex (TDM)device to a SIP device, in accordance with an exemplary embodiment. Asillustrated in FIG. 4A, the time-division multiplexing (TDM) device 118may be operatively coupled to the SIP Network 120 via a gateway 402. Thegateway 402 may be an interface between a network (e.g., a time-divisionmultiplexing network) associated with the auxiliary end terminal A2 104and the SIP Network 120. For example, the time-division multiplexing(TDM) device 118 may initiate a SIP session (e.g., telephone callsession) by transmitting an initial address message (IAM) to the gateway402. The initial address message (IAM) may include an identification ofthe auxiliary end terminal A2 104, an identification of the end terminalB 106, setting associated with various network elements of system 100,and/or other information necessary to initiate a SIP session. Theinitial address message (IAM) may not be in the SIP format and thegateway 402 may convert the initial address message (IAM) into a SIPbased message (e.g., an Invite message). The gateway 402 may transmitthe Invite message to the SIP server 122. Upon receiving the Invitemessage, the SIP server 122 may transmit a return message (e.g., 100Trying message) back to the gateway 402 to acknowledge the reception ofthe Invite message. The SIP server 122 may transmit the Invite messageto the end terminal B 106 via a generic box 406. The generic box 406 maybe an element in the SIP network 124 (e.g., SBC) and/or an elementassociated with the SIP Element 130 and/or the SIP Element 132 (e.g.,IPPBX). Upon receiving the Invite message from the SIP server 122, thegeneric box 406 may transmit a return message (e.g., 100 Trying message)back to the SIP server 122 to acknowledge the reception of the Invitemessage. The generic box 406 may transmit the Invite message to the endterminal B 106. Also, the generic box 406 may transmit the Invitemessage to the next network element along a transmission path from theauxiliary end terminal A2 104 towards the end terminal B 106. In anexemplary embodiment, the 100 Trying messages are transmitted by variousnetwork elements along the transmission path in the system 100 to onlycontiguous network elements of the system 100 in order to acknowledgethe reception of the Invite message. Therefore, the interactions betweenthe various network elements of the system 100 may be limited and theSIP server 122 may not know the condition/status of various networkelements down the transmission path of the system 100.

In the event that the end terminal B 106 does not respond, the genericbox 406 may retransmit the Invite message at various time intervals. Inan exemplary embodiment, in the first time interval the generic box 406may wait for a half of a second before retransmitting the Invitemessage. In the second time interval, the generic box 406 may double thetimeframe and wait for one second before retransmitting the Invitemessage. In the subsequent time intervals, the generic box 406 maydouble the timeframe and wait for two seconds, four seconds, and eightseconds, etc, before retransmitting the Invite message. For example, thegeneric box 406 may retransmit the Invite message for a predeterminednumber of time intervals. Also, the generic box 406 may retransmit theInvite message until instructed otherwise by various network elementsbetween the auxiliary end terminal A2 104 and the end terminal B 106.For example, the auxiliary end terminal A2 104 may instruct the genericbox 406 to terminate the session initiation process.

In the event that the end terminal B 106 does not respond after apredetermined time intervals and/or the SIP device 110 terminates theSIP session initiation process, the generic box 406 may terminateretransmitting the Invite message. A release message (REL) or a cancelmessage may be transmitted by the time-division multiplexing (TDM)device 118 to terminate the session initiation process. Also, variousnetwork elements along the transmission path between the auxiliary endterminal A2 104 and/or the end terminal B 106 may transmit a releasemessage (REL) or a cancel message to terminate the session initiationprocess. The release message (REL) or the cancel message may include anidentification of the auxiliary end terminal A2 104, an identificationof the end terminal B 106, setting associated with various networkelements of system 100, and/or other information necessary to terminatea session. For example, the release message or the cancel message may betransmitted from the time-division multiplexing (TDM) device 118 and/ora network associated with the time-division multiplexing (TDM) device118. Also, the release message (REL) or the cancel message may betransmitted by various network elements (not shown) between the gateway402 and the user associated with the time-division multiplexing (TDM)device 118. In an exemplary embodiment, the release message (REL) or thecancel message may not be in the SIP format and the gateway 402 mayconvert the release message (REL) to a cancel message in the SIP format.The gateway 402 may transmit the cancel message to the SIP server 122,and the SIP server 122 may transmit a return message (e.g., 200 OKmessage) to acknowledge the reception of the cancel message. The SIPserver 122 may transmit the cancel message to the generic box 406 andthe generic box 406 may transmit a return message (e.g., 200 OK message)to acknowledge the reception of the cancel message. As shown the genericbox 406 may receive the cancel message before the final retransmissionof the Invite message. It may be appreciated by one of ordinary skill inthe art that, the generic box 406 may receive the cancel message duringany retransmission time interval. In a particular exemplary embodiment,the session initiation process failed because the end terminal B 106fails to respond to the Invite message. Thus, the user associated withthe time-division multiplexing (TDM) device 118 has to wait for a longtime (e.g., several seconds or minutes) and yet fails to determine thestatus (e.g., unavailable and/or not functioning) of the end terminal B106.

In an exemplary embodiment, the timer module 116 may be associated withvarious network elements along the transmission path between theauxiliary end terminal A2 104 and the end terminal B 106. For example,the timer module 116 may include a single timer located at one of thegateway 402, the SIP server 122, the generic box 406 and/or othernetwork elements of the system 100. Also, the timer module 116 mayinclude a plurality of timers located at one of the gateway 402, the SIPserver 122, the generic box 406 and/or other network elements of thesystem 100. In an exemplary embodiment, the timer module 116 may includethree timers (e.g., Timer B, Timer B Minus, and Timer 100 Next) locatedat the SIP server 122. For example, each of the three timers of thetimer module 116 may be set to expire after a predetermined time period.The predetermined time period of each of the three timers of the timermodule 116 may be set by a user associated with the auxiliary endterminal A2 104, a user associated with the end terminal B 106. Also,the predetermined time period of each of the three timers of the timermodule 116 may be set by a network administrator associated with the SIPserver 122 and/or the disparate entity. Moreover, the predeterminedtimer period of each of the three timers of the timer module 116 mayvary based at least in part on the type of session (e.g., two users callsession, more than two users call session). In an exemplary embodiment,the predetermined timer period of each of the three timers of the threetimer module 116 may be set to a longer period of time as number ofusers associated with the session increase.

In an exemplary embodiment, a first timer (e.g., Timer B) may be a SIPtimer located at the SIP server 122 and may start counting upontransmission of the Invite signal and stop counting upon the receptionof a return message (e.g., a 100 Trying message and/or other returnmessages) from the generic box 406. The first timer may determinewhether the generic box 406 will continue the retransmission of theInvite message in the event that no response is received from the endterminal B 106. For example, the generic box 406 may continue toretransmit the Invite message in the event that the first timer has notexpired (e.g., continuously counting or stopped counting before thepredetermined time period). Also, the generic box 406 may stopretransmitting the Invite message and declare session initiation processfailed, in the event that the first timer expired.

In an exemplary embodiment, a second timer (e.g., Timer B minus) may bea SIP timer located at the SIP server 122 and may start counting at thesame time as the first timer or at a time the Invite message istransmitted by the SIP server 122. The predetermined expiration timeperiod of the second timer may be shorter or longer than or the same asthe predetermined expiration time period of the first timer. Forexample, the predetermined expiration time period of the second timermay be shorter than the predetermined expiration time period of thefirst timer in order to reduce the wait time of the user associated withthe time-division multiplexing (TDM) device 118. The second timer maystop counting upon the reception of a return message (e.g., a connectedmessage). However, the second timer may disregard the reception of areturn message (e.g., 100 Trying message) from the generic box 406acknowledging the reception of the Invite message and may continuecounting. Also, the second timer may stop counting upon the reception ofan end to end message (e.g., establishment of session message).Therefore, the second timer may disregard the return message (e.g., 100Trying message) between two contiguous network elements because thereturn message fails to indicate the status/condition (e.g., unavailableand/or not functioning) of the end terminal B 106. The second timer maydisregard the return message (e.g., 100 Trying message) from contiguousnetwork elements because the return message may be misleading. Thereturn message from contiguous network elements (e.g., 100 Tryingmessage) may only indicate the status of two contiguous network elementsand fails to indicate the status of all end to end network elements.Thus, even though the end terminal B 106 may not respond to the Invitemessage, the return message from contiguous network elements (e.g., 100Trying message) may gave the misleading impression that the end terminalB 106 have responded to the Invite message.

Further, the timer module 116 may include a third timer (e.g., Timer 100Next) positioned at the SIP server 122. The predetermined expirationtime period of the third timer may be shorter or longer than or the sameas the predetermined expiration time period of the first timer and/orthe second timer. In an exemplary embodiment, the predeterminedexpiration time period of the third timer may be shorter than thepredetermined expiration time period of the first timer. Also, thepredetermined expiration time period of the third timer may be shorterthan the predetermined expiration time period of the second timer. Inanother exemplary embodiment, the predetermined expiration time periodof the third timer may be longer than the predetermined expiration timeperiod of the second timer. For example, the third timer may startcounting upon reception of a return messages (e.g., 100 Trying message)from contiguous network elements acknowledging the reception of theInvite message and stop counting upon the reception of other returnmessages (e.g., a connected message). In an exemplary embodiment, thethird timer may start counting only at the reception of the returnmessage (e.g., 100 Trying message) from contiguous network elementsacknowledging the reception of the Invite message and may stop countingupon the reception of an end to end message (e.g., establishment ofsession message).

In an exemplary embodiment, the first timer, the second timer, and/orthe third timer of the timer module 116 may be located at variousnetwork elements of the system 100 and may be set to expire at disparatepredetermined time periods. Also, the predetermined time periods for thefirst timer, the second timer, and/or the third timer located at variousnetwork elements of the system 100 may be set dynamically based at leastin part on the session (e.g., number of user, type of session). Forexample, the first timer may be set to expire approximately 32 secondsafter the initial Invite message was sent. The second timer may be setto expire, for example, 20 seconds, after the initial Invite message.Also, the third timer may be set to expire, for example, 25 seconds,after the initial Invite message. Also, the first timer, the secondtimer and/or the third timer of the timer module 116 may be set toexpire at different times based at least in part on the location of thenetwork elements of the system 100. For example, the first timer locatedat the gateway 402 may be set to expire approximately 60 seconds, thefirst timer located at the SIP server 122 may be set to expireapproximately 40 seconds, and/or the first timer located at the genericbox 406 may be set to expire approximately 50 seconds. Also, forexample, the second timer located at the gateway 402 may be set toexpire approximately 30 seconds, the second timer located at the SIPserver 122 may be set to expire approximately 35 seconds, and/or thesecond timer located at the generic box 406 may be set to expireapproximately 25 seconds. Further, for example, the third timer locatedat the gateway 402 may be set to expire approximately 40 seconds, thethird timer located at the SIP server 122 may be set to expireapproximately 30 seconds, and/or the third timer located at the genericbox 406 may be set to expire approximately 30 seconds. In anotherexemplary embodiment, the first timer, the second timer, and/or thethird timer of the timer module 116 located at various network elementsof the system 100 may be independent of each other. For example, thefirst timer, the second timer, and/or the third timer may be located atthe gateway 402, the SIP server 122, the generic box 406, and/or othernetwork elements of the system 100. As described above, the first timer,the second timer, and/or the third timer may be set to expire atdisparate time periods. Therefore, the first expired timer may take oneor more overflow actions (e.g., terminate the SIP session initiationprocess, redirect the Invite message) and/or transmit one or moremessages/signals to various network elements of system 100 to take oneor more overflow actions.

In an exemplary embodiment, the expired timer may transmit one or moremessages/signals to the various network elements (e.g., SIP server 122)of system 100 to take one or more overflow actions. Also, the expiredtimer may take one or more overflow actions. For example, upon theexpiration of the timer, the SIP server 122 may determine that the endterminal B 106 is not responding and may decide to take one or moreoverflow actions. For example, the one or more overflow actions mayinclude the SIP server 122 connecting the time-division multiplexing(TDM) device 118 to a media server (not shown) and play one or moremessages. The one or more messages may inform the user associated withthe time-division multiplexing (TDM) device 118 to “please hold, we'rehaving difficulty reaching the called party.” Also, the expired timermay transmit one or more messages/signals to various network elements ofsystem 100 to take one or more overflow actions. The one or moremessages/signals may inform the various network elements of the system100 that the end terminal B 106 is unavailable and/or not functioning.Further, the one or more messages/signals may prevent one or morenetwork elements (e.g., time-division multiplexing (TDM) device 118and/or gateway 402) of the system 100 from transmitting a Releasemessage (REL) and/or the cancel message. Moreover, the expired timer maynot take any overflow action and wait for the transmission of theRelease message (REL) by the time-division multiplexing (TDM) device118. In another exemplary embodiment, the expired timer may transmit oneor more messages/signals to various network elements of the system 100to redirect the Invite message to another party. For example, thetime-division multiplexing (TDM) device 118 may transmit an Invitemessage to the SIP Element 130 and upon the expiration of the firsttimer, the second timer, and/or the third timer of the timer module 116,one or more messages/signals may be transmitted to various networkelements of the system 100. The one or more messages/signals mayinstruct the various network elements of the system 100 to redirect theInvite message to SIP Element 132.

FIG. 4B illustrates a flow diagram for providing integrated setup timersin a SIP-based network for connecting a first SIP device to a second SIPdevice, in accordance with an exemplary embodiment. As illustrated inFIG. 4B, the SIP device 110 may be operatively coupled to the SIP server122 via a SIP Network 120. The SIP device 110 may be associated with theauxiliary end terminal A1 104 and the SIP Network 120. For example, theSIP device 110 may initiate a SIP session (e.g., a call session, a datatransmission session, and/or a video session) by transmitting a SIPbased message (e.g., an Invite message). The Invite message may includean identification of the auxiliary end terminal A1 104, anidentification of the end terminal B 106, setting associated withvarious network elements of system 100, and/or other informationnecessary to initiate a SIP session. The SIP device 110 may transmit theInvite message to the SIP server 122 via the SIP Network 120. Uponreceiving the Invite message, the SIP server 122 may transmit a returnmessage (e.g., 100 Trying message) back to the SIP device 110 toacknowledge the reception of the Invite message. The SIP server 122 maytransmit the Invite message to the end terminal B 106 via a generic box406. The generic box 406 may be an element in the SIP network 124 (e.g.,SBC) and/or an element associated with the SIP Element 130 and/or theSIP Element 132 (e.g., IPPBX). Upon receiving the Invite message fromthe SIP server 122, the generic box 406 may transmit a return message(e.g., 100 Trying message) back to the SIP server 122 to acknowledge thereception of the Invite message. The generic box 406 may transmit theInvite message to the end terminal B 106. Also, the generic box 406 maytransmit the Invite message to the next network element along atransmission path from the auxiliary end terminal A1 104 towards the endterminal B 106. In an exemplary embodiment, the 100 Trying messages aretransmitted by various network elements along the transmission path inthe system 100 to only contiguous network elements of the system 100 inorder to acknowledge the reception of the Invite message. Therefore, theinteractions between the various network elements of the system 100 maybe limited and the SIP server 122 may not know the condition/status ofvarious network elements down the transmission path of the system 100.

In the event that the end terminal B 106 does not respond, the genericbox 406 may retransmit the Invite message at various time intervals. Inan exemplary embodiment, in the first time interval the generic box 406may wait for a half of a second before retransmitting the Invitemessage. In the second time interval, the generic box 406 may double thetimeframe and wait for one second before retransmitting the Invitemessage. In the subsequent time intervals, the generic box 406 maydouble the timeframe and wait for two seconds, four seconds, and eightseconds, etc, before retransmitting the Invite message. For example, thegeneric box 406 may retransmit the Invite message for a predeterminednumber of time intervals. Also, the generic box 406 may retransmit theInvite message until instructed otherwise by various network elementsbetween the auxiliary end terminal A1 104 and the end terminal B 106.For example, the auxiliary end terminal A1 104 may instruct the genericbox 406 to terminate the SIP session initiation process.

In the event that the end terminal B 106 does not respond after apredetermined time intervals and/or the SIP device 110 terminates theSIP session initiation process, the generic box 406 may terminateretransmitting the Invite message. A cancel message may be transmittedby the SIP server 122 to terminate the SIP session initiation process.Also, various network elements along the transmission path between theauxiliary end terminal A1 104 and/or the end terminal B 106 may transmitthe cancel message to terminate the SIP session initiation process. Thecancel message may include an identification of the auxiliary endterminal A1 104, an identification of the end terminal B 106, settingassociated with various network elements of system 100, and/or otherinformation necessary to terminate a SIP session. For example, thecancel message may be transmitted from the SIP device 110 and/or anetwork associated with the SIP device 110. Also, the cancel message maybe transmitted by various network elements (not shown) between the userassociated with the SIP device 110 and the SIP server 122. SIP device110 may transmit the cancel message to the SIP server 122, and the SIPserver 122 may transmit a return message (e.g., 200 OK message) toacknowledge the reception of the cancel message. The SIP server 122 maytransmit the cancel message to the generic box 406 and the generic box406 may transmit a return message (e.g., 200 OK message) to acknowledgethe reception of the cancel message. As shown the generic box 406 mayreceive the cancel message before the final retransmission of the Invitemessage. It may be appreciated by one of ordinary skill in the art that,the generic box 406 may receive the cancel message during anyretransmission time interval. In a particular exemplary embodiment, theSIP session initiation process failed because the end terminal B 106fails to respond to the Invite message. Thus, the user associated withthe SIP device 110 has to wait for a long time (e.g., several seconds orminutes) and yet fails to determine the status (e.g., unavailable and/ornot functioning) of the end terminal B 106.

In an exemplary embodiment, the timer module 116 may be associated withvarious network elements along the transmission path between theauxiliary end terminal A1 104 and the end terminal B 106. For example,the timer module 116 may include a single timer located at one of theSIP server 122, the generic box 406 and/or other network elements of thesystem 100. Also, the timer module 116 may include a plurality of timerslocated at one of the SIP server 122, the generic box 406 and/or othernetwork elements of the system 100. In an exemplary embodiment, thetimer module 116 may include three timers (e.g., Timer B, Timer B Minus,and Timer 100 Next) located at the SIP server 122. For example, each ofthe three timers of the timer module 116 may be set to expire after apredetermined time period. The predetermined time period of each of thethree timers of the timer module 116 may be set by a user associatedwith the auxiliary end terminal A1 104, a user associated with the endterminal B 106. Also, the predetermined time period of each of the threetimers of the timer module 116 may be set by a network administratorassociated with the SIP server 122 and/or the disparate entity.Moreover, the predetermined timer period of each of the three timers ofthe timer module 116 may vary based at least in part on the type of SIPsession (e.g., two user SIP session, more than two users SIP session).

In an exemplary embodiment, a first timer (e.g., Timer B) may be a SIPtimer located at the SIP server 122 and may start counting upontransmission of the Invite signal and stop counting upon the receptionof a return message (e.g., a 100 Trying message and/or other returnmessages) from the generic box 406. The first timer may determinewhether the generic box 406 will continue the retransmission of theInvite message in the event that no response is received from the endterminal B 106. For example, the generic box 406 may continue toretransmit the Invite message in the event that the first timer has notexpired (e.g., continuously counting or stopped counting before thepredetermined time period). Also, the generic box 406 may stopretransmitting the Invite message and declare SIP session initiationprocess failed, in the event that the first timer expired.

In an exemplary embodiment, a second timer (e.g., Timer B minus) may bea SE timer located at the SIP server 122 and may start counting at thesame time as the first timer or at a time the Invite message istransmitted by the SIP server 122. The predetermined expiration timeperiod of the second timer may be shorter or longer than or the same asthe predetermined expiration time period of the first timer. Forexample, the predetermined expiration time period of the second timermay be shorter than the predetermined expiration time period of thefirst timer in order to reduce the wait time of the user associated withthe SIP device 110. The second timer may stop counting upon thereception of a return message (e.g., a connected message). However, thesecond timer may disregard the reception of a return message (e.g., 100Trying message) from the generic box 406 acknowledging the reception ofthe Invite message and may continue counting. Also, the second timer maystop counting upon the reception of an end to end message (e.g.,establishment of SIP session message). Therefore, the second timer maydisregard the return message (e.g., 100 Trying message) between twocontiguous network elements because the return message fails to indicatethe status/condition (e.g., unavailable and/or not functioning) of theend terminal B 106. The second timer may disregard the return message(e.g., 100 Trying message) from contiguous network elements because thereturn message may be misleading. The return message from contiguousnetwork elements (e.g., 100 Trying message) may only indicate the statusof two contiguous network elements and fails to indicate the status ofall end to end network elements. Thus, even though the end terminal B106 may not respond to the Invite message, the return message fromcontiguous network elements (e.g., 100 Trying message) may gave themisleading impression that the end terminal B 106 have responded to theinvite message.

Further, the timer module 116 may include a third timer (e.g., Timer 100Next) positioned at the SIP server 122. The predetermined expirationtime period of the third timer may be shorter or longer than or the sameas the predetermined expiration time period of the first timer and/orthe second timer. In an exemplary embodiment, the predeterminedexpiration time period of the third timer may be shorter than thepredetermined expiration time period of the first timer. Also, thepredetermined expiration time period of the third timer may be shorterthan the predetermined expiration time period of the second timer. Inanother exemplary embodiment, the predetermined expiration time periodof the third timer may be longer than the predetermined expiration timeperiod of the second timer. For example, the third timer may startcounting upon reception of a return messages (e.g., 100 Trying message)from contiguous network elements acknowledging the reception of theInvite message and stop counting upon the reception of other returnmessages (e.g., a connected message). In an exemplary embodiment, thethird timer may start counting only at the reception of the returnmessage (e.g., 100 Trying message) from contiguous network elementsacknowledging the reception of the Invite message and may stop countingupon the reception of an end to end message (e.g., establishment of SIPsession message).

In an exemplary embodiment, the first timer, the second timer, and/orthe third timer of the timer module 116 may be located at variousnetwork elements of the system 100 and may be set to expire at disparatepredetermined time periods. Also, the predetermined time periods for thefirst timer, the second timer, and/or the third timer located at variousnetwork elements of the system 100 may be set dynamically based at leastin part on the SIP session (e.g., number of user, type of SIP session).For example, the first timer may be set to expire approximately 32seconds after the initial Invite message was sent. The second timer maybe set to expire, for example, 20 seconds, after the Initial message.Also, the third timer may be set to expire, for example, 25 seconds,after the Initial message was sent. Also, the first timer, the secondtimer and/or the third timer of the timer module 116 may be set toexpire at different times based at least in part on the location of thenetwork elements of the system 100. For example, the first timer locatedat the SIP device 110 may be set to expire approximately 60 seconds, thefirst timer located at the SIP server 122 may be set to expireapproximately 40 seconds, and/or the first timer located at the genericbox 406 may be set to expire approximately 50 seconds. Also, forexample, the second timer located at the SIP device 110 may be set toexpire approximately 30 seconds, the second timer located at the SIPserver 122 may be set to expire approximately 35 seconds, and/or thesecond timer located at the generic box 406 may be set to expireapproximately 25 seconds. Further, for example, the third timer locatedat SIP device 110 may be set to expire approximately 40 seconds, thethird timer located at the SIP server 122 may be set to expireapproximately 30 seconds, and/or the third timer located at the genericbox 406 may be set to expire approximately 30 seconds. In anotherexemplary embodiment, the first timer, the second timer, and/or thethird timer of the timer module 116 located at various network elementsof the system 100 may be independent of each other. For example, thefirst timer, the second timer, and/or the third timer may be located atthe SIP device 110, the SIP server 122, the generic box 406, and/orother network elements of the system 100. As described above, the firsttimer, the second timer, and/or the third timer may be set to expire atdisparate time periods. Therefore, the first expired timer may take oneor more overflow actions (e.g., terminate the SIP session initiationprocess, redirect the Invite message) and/or transmit one or moremessages/signals to various network elements of system 100 to take oneor more overflow actions.

In an exemplary embodiment, the expired timer may transmit one or moremessages/signals to the various network elements (e.g., SIP server 122)of system 100 to take one or more overflow actions. Also, the expiredtimer may take one or more overflow actions. For example, upon theexpiration of the timer, the SIP server 122 may determine that the endterminal B 106 is not responding and may decide to take one or moreoverflow actions. For example, the one or more overflow actions mayinclude the SIP server 122 connecting the SIP device 110 to a mediaserver (not shown) and play one or more messages. The one or moremessages may inform the user associated with the SIP device 110 to“please hold, we're having difficulty reaching the called party.” Also,the expired timer may transmit one or more messages/signals to variousnetwork elements of system 100 to take one or more overflow actions. Theone or more messages/signals may inform the various network elements ofthe system 100 that the end terminal B 106 is unavailable and/or notfunctioning. Further, the one or more messages/signals may prevent oneor more network elements (e.g., SIP device 110 and/or SIP server 122) ofthe system 100 from transmitting a cancel message. Moreover, the expiredtimer may not take any overflow action and wait for the transmission ofthe cancel message by the SIP device 110. In another exemplaryembodiment, the expired timer may transmit one or more messages/signalsto various network elements of the system 100 to redirect the Invitemessage to another party. For example, the SIP device 110 may transmitan Invite message to the SIP Element 130 and upon the expiration of thefirst timer, the second timer, and/or the third timer of the timermodule 116, one or more messages/signals may be transmitted to variousnetwork elements of the system 100. The one or more messages/signals mayinstruct the various network elements of the system 100 to redirect theInvite message to SIP Element 132.

FIG. 5A illustrates a flow diagram for providing independent setuptimers in a SIP-based network for connecting a time-divisionmultiplexing (TDM) device to a SIP device, in accordance with anexemplary embodiment. As illustrated, the first timer, the second timer,and/or the third timer of the timer module 116 may be implemented asindependent network elements of the system 100. As described above, thefirst timer, the second timer, and/or the third timer of the timermodule 116 may be set to expire at disparate periods of time. Uponexpiration of the first timer, the second timer, and/or the third timer,the first and/or any subsequent expired timers may transmit one or moremessages/signals to various network elements in the system 100 to takeone or more overflow actions. In an exemplary embodiment, the firsttimer, the second timer, and/or the third timer may be provided at anylocation in the system 100. As illustrated, the timer module 116 may beprovided between the SIP server 122 and the generic box 406. Also, thetimer module 116 may be provided between the SIP device 110 and the SIPserver 122. In a particular exemplary embodiment, the first timer andthe second timer of the timer module 116 may start counting upon thereception of the Invite message and the third timer of the timer module116 may start counting upon the reception of a return message (e.g., 100Trying message) from contiguous network elements acknowledging thereception of the Invite message. In an exemplary embodiment, the secondtimer and/or the third timer may be set to expire after a shorter timeperiod than the first timer. By setting the second timer and/or thethird timer to expire after a shorter time period than the first timer,the user associated with SIP device 110 may be notified of none responsefrom the end terminal B 106. In another exemplary embodiment, the secondtimer and the third timer may set to expire after the same time period.In the event that the second timer and the third timer expire after thesame time period, the second timer and/or the third timer may transmitone or more messages/signals to various network elements of the system100 to take one or more overflow actions.

FIG. 5B illustrates a flow diagram for providing independent setuptimers in a SIP-based network for connecting a first SIP device to asecond SIP device, in accordance with an exemplary embodiment. Asillustrated, the first timer, the second timer, and/or the third timerof the timer module 116 may be implemented as independent networkelements of the system 100. As described above, the first timer, thesecond timer, and/or the third timer of the timer module 116 may be setto expire at disparate periods of time. Upon expiration of the firsttimer, the second timer, and/or the third timer, the first and/or anysubsequent expired timers may transmit one or more messages/signals tovarious network elements in the system 100 to take one or more overflowactions. In an exemplary embodiment, the first timer, the second timer,and/or the third timer may be provided at any location in the system100. As illustrated, the timer module 116 may be provided between theSIP server 122 and the generic box 406. Also, the timer module 116 maybe provided between the SIP device 110 and the SIP server 122. In aparticular exemplary embodiment, the first timer and the second timer ofthe timer module 116 may start counting upon the reception of the Invitemessage and the third timer of the timer module 116 may start countingupon the reception of a return message (e.g., 100 Trying message) fromcontiguous network elements acknowledging the reception of the Invitemessage. In an exemplary embodiment, the second timer and/or the thirdtimer may be set to expire after a shorter time period than the firsttimer. By setting the second timer and/or the third timer to expireafter a shorter time period than the first timer, the user associatedwith SIP device 110 may be notified of none response from the endterminal B 106. In another exemplary embodiment, the second timer andthe third timer may set to expire after the same time period. In theevent that the second timer and the third timer expire after the sametime period, the second timer and/or the third timer may transmit one ormore messages/signals to various network elements of the system 100 totake one or more overflow actions.

FIG. 6 illustrates a flow diagram of a method for implementing SIP setuptimers in accordance with exemplary embodiments. This exemplary methodis provided by way of example, as there are a variety of ways to carryout methods disclosed herein. The method 600 shown in FIG. 6 can beexecuted or otherwise performed by one or a combination of varioussystems. The method 600 is described below as carried out by the system100 shown in FIG. 1 by way of example, and various elements of thesystem 100 are referenced in explaining the example method of FIG. 6.Each block shown in FIG. 6 represents one or more processes, methods, orsubroutines carried in the exemplary method 600. Referring to FIG. 6,the exemplary method 600 may begin at block 602.

At block 602, a user may request to establish a session (e.g., a callsession, a data transmission session, a video session). For example, auser located at end terminal A 104 (e.g., auxiliary end terminal A1 104and/or auxiliary end terminal A2 104) may utilize the SIP device 110and/or the time-division multiplexing (TDM) device 118 to initiate thesession. In an exemplary embodiment, the SIP device 110 may transmit aSIP based message (e.g., an Invite message) to various network elementsof system 100. In another exemplary embodiment, the time-divisionmultiplexing (TDM) device 118 may generate and/or transmit an initialaddress message (IAM) to the gateway 402. The initial address message(IAM) may not be in the SIP format and the gateway 402 may convert theinitial address message (IAM) into a SIP based message (e.g., an Invitemessage). In an exemplary embodiment, the user may enter a phone numberto initiate a SIP session. The method 600 may continue to block 604.

At block 604, one or more timers of the timer module 116 may startcounting upon the reception of one or more messages. In an exemplaryembodiment, the timer module 116 may include a plurality of timers. Forexample, a first timer (e.g., Timer B) of the timer module 116 may be aSIP timer and may start counting upon transmission of the Invite signaland stop counting upon the reception of a return message (e.g., a 100Trying message and/or other return messages). The second timer (e.g.,Timer B minus) of the timer module 116 may be a SIP timer and may startcounting at the same time as the first timer or at a time oftransmission of the Invite message. Also, a third timer of the timermodule 116 may start counting upon the reception of a return message(e.g., 100 Trying message) from contiguous network elementsacknowledging the reception of the Invite message. The plurality oftimers of the timer module 116 may be provided at various locations inthe system 100 and may be set to expire at disparate time periods. Themethod 600 may continue to block 606.

At block 606, the expired timer may transmit one or moremessages/signals to various network elements in the system 100. Forexample, the first timer may be set to expire after 32 seconds, thesecond timer may be set to expire after 20 seconds, and/or the thirdtimer may be set to expire after 15 seconds. The first expired timer maytransmit one or more messages/signals to the gateway 402 (e.g.,associated with the time-division multiplexing (TDM) device 118), theSIP server 122, the generic box 406, and/or other network elements ofsystem 100 to take one or more overflow actions. Also, the expired timermay not transmit one or more messages/signals to take one or moreoverflow actions. The method 600 may continue to block 608.

At block 608, various network elements of the system 100 may take one ormore overflow actions. For example, various network elements of thesystem 100 may receive one or more messages/signal from an expired timerof the timer module 116. The various network elements of the system 100may store predetermined logic to take one or more overflow actions. Inan exemplary embodiment, the one or more overflow actions may includeinforming the user located at the end terminal A 104 (e.g., auxiliaryend terminal A1 104 and/or auxiliary end terminal A2 104) to “pleasehold, we're having difficulty reaching the called party.” Also, the oneor more overflow actions may include informing the various networkelements of the system 100 that the end terminal B 106 is unavailableand/or not functioning. Further, the one or more overflow actions mayinclude redirecting the Invite message from a first SIP element to asecond SIP element. For example, the SIP device 110 may transmit theInvite message to the SIP Element 130 and upon the expiration of thefirst timer, the second timer, and/or the third timer, one or moremessages/signals may be transmitted to various network elements of thesystem 100. In another exemplary embodiment, the time-divisionmultiplexing (TDM) device 118 may transmit the initial address message(e.g., the Invite message) to the SIP Element 130 and upon theexpiration of the first timer, the second timer, and/or the third timer,one or more messages/signals may be transmitted to various networkelements of the system 100. The various network elements of the system100 may redirect the Invite message to the SIP Element 132.

In the preceding specification, various preferred embodiments have beendescribed with reference to the accompanying drawings. It will, however,be evident that various modifications and changes may be made thereto,and additional embodiments may be implemented, without departing fromthe broader scope of the invention as set forth in the claims thatfollow. The specification and drawings are accordingly to be regarded inan illustrative rather than restrictive sense.

The invention claimed is:
 1. A method, comprising: attempting toinitiate a session where a communication session is not already inprogress by transmitting one or more messages to a device associatedwith a first user; starting a first SIP timer upon transmitting the oneor more messages and stopping the first timer upon receiving a returnmessage, wherein the first timer is configured to expire if the returnmessage is not received after a first predetermined time period andwherein the return message is an acknowledgement message of reception ofthe one or more messages; starting a second SIP timer upon transmittingthe one or more messages, wherein the second timer is configured toexpire after a second predetermined time period; transmitting one ormore overflow instructions upon expiration of at least one of the firsttimer and the second timer, wherein the expiration of the at least oneof the first timer and the second timer indicates an overflow action isnecessary because a session has not been initiated; and taking one ormore overflow actions based at least in part on the one or more overflowinstructions, wherein the one or more actions comprises at least one ofplaying a pre-recorded message and redirecting the session to a seconduser.
 2. The method of claim 1, wherein the first predetermined timeperiod is greater than the second predetermined time period.
 3. Themethod of claim 1, wherein the session is at least one of a callsession, a data transmission session, and a video session.
 4. The methodof claim 1, wherein the second timer continues to count after receptionof the return message from a contiguous network element.
 5. The methodof claim 1, wherein the return message is the acknowledgement message ofreception of the one or more messages by a contiguous network element.6. The method of claim 1, further comprises starting a third timer,wherein the third timer is configured to expire after a thirdpredetermined time period.
 7. The method of claim 6, wherein starting athird timer comprises starting the third timer in response to receivingthe return message from a contiguous network element.
 8. The method ofclaim 1, wherein the second predetermined time period is based at leastin part on number of users and type of the session.
 9. A non-transitorycomputer readable media comprising code to perform the steps of themethods of claim
 1. 10. A system, comprising: a device configured toattempt to establish a session where a communication session is notalready in progress, by transmitting one or more messages to a deviceassociated with a first user; a first SIP timer configured to start inresponse to transmitting the one or more messages and stop in responseto reception of a return message, wherein the first timer expires if thereturn message is not received after a first predetermined time periodand wherein the return message is an acknowledgement message ofreception of the one or more messages; a second SIP timer configured tostart in response to transmitting the one or more messages and expireafter a second predetermined time period and transmit one or moreoverflow instructions upon expiration of the second predetermined timeperiod, wherein the expiration of at least one of the first timer andthe second timer indicates an overflow action is necessary because asession has not been initiated; and one or more network elementsconfigured to take one or more overflow actions based at least in parton the one or more overflow instructions, wherein the one or moreactions comprises at least one of playing a pre-recorded message andredirecting the session to a second user.
 11. The system of claim 10,wherein the first predetermined time period is greater than the secondpredetermined time period.
 12. The system of claim 10, wherein thesession is at least one of a call session, a data transmission session,and a video session.
 13. The system of claim 10, wherein the secondtimer is configured to continue counting after reception of the returnmessage from a contiguous network element.
 14. The system of claim 10,wherein the return message is the acknowledgement message of receptionof the one or more messages by a contiguous network element.
 15. Thesystem of claim 10, further comprises a third timer configured expireafter a third predetermined time period, wherein the third predeterminedtime period is shorter than the first predetermined time period.
 16. Thesystem of claim 15, wherein the third timer is configured to start inresponse to receiving the return message from a contiguous networkelement.
 17. The system of claim 15, wherein at least one of the firsttimer, the second timer, and the third timer is integrated with one ormore network elements.
 18. The system of claim 15, wherein at least oneof the first timer, the second timer, and the third timer is independentof one or more network elements.
 19. The system of claim 10, wherein thesecond predetermined time period is based at least in part on number ofusers and type of the session.
 20. The method of claim 6, wherein thethird predetermined time period is different from at least one of thefirst predetermined time period and the second predetermined timeperiod.
 21. The system of claim 15, wherein the third predetermined timeperiod is different from the second predetermined time period.
 22. Themethod of claim 1, wherein the first timer is configured to expirewithin sixty seconds.
 23. The method of claim 22, wherein the secondtimer is configured to expire within fifty seconds.
 24. The method ofclaim 1, wherein the overflow instructions are transmitted uponexpiration of the second timer.